1. Gene Expression & Mutations
SB2. Students will analyze how biological traits are passed on to successive generations.
(d) Describe the relationships between changes in DNA and potential appearance of new traits including:
- Alterations during replication (Insertions, Deletions, Substitutions)
Mutagenic factors that can alter DNA (High energy radiation and Chemical)

2. Protein Synthesis REVIEW
Genes are small segments of DNA that code for proteins
The process of protein synthesis consists of two steps:
Transcription
An mRNA molecule is transcribed from a DNA template.
This happens in the nucleus.
Translation
The coordination of tRNA and mRNA create a strand of amino acids known as a polypeptide chain.
This happens on a ribosome.

3. Control of Gene Expression
In prokaryotes, proteins interacting with DNA turn prokaryotic genes on or off in response to environmental changes
Differentiation yields a variety of cell types, each expressing a different combination of genes
In multicellular eukaryotes, cells become specialized as a zygote develops into a mature organism
Different types of cells make different kinds of proteins
Different combinations of genes are active in each type
Most differentiated cells retain a complete set of genes
In general, all somatic cells of a multicellular organism have the same genes

4. Control of Gene Expression

5. Amoeba Sisters: Mutations

6. Genetic Changes What is a mutation?
A mistake or change in the genetic (DNA) make-up of an organism
There are four different types of mutations
Point mutations
Frameshift mutations
Chromosomal mutations
Spontaneous mutations
Mutation Story
QUESTIONS TO PONDER WHILE WATCHING “MUTATION STORY”
How can a mutation be harmful in one environment and helpful in another?
Why should a mutation persist if it kills people?
Why are there more people with sickle cell disease in one part of the world than in other parts?

7. Mutation Story

8. Point & Frameshift Mutations
Point mutation
Change in a single base pair in DNA
THEDOGBITTHECAT
Change the ending “T” to a “R”
THEDOGBITTHECAR
Frameshift mutation
A shift in one place (deletions/insertions)
HAVEANICEDAY
Delete the “N” and shift everything down
HAVEAICEDAY

10. Nonsense vs. Missense Mutations
The new codon causes the protein to prematurely terminate, producing a product that is shortened and often does not function.
MISSENSE
The new codon causes an incorrect amino acid to be inserted into the protein. The effects on the function of the protein depend on what is inserted in place of the normal amino acid.

11. Chromosomal Mutation Chromosomes are physically changed Trisomy
May break and rejoin incorrectly
May not separate correctly (or at all) during Meiosis  NONDISJUNCTION
Trisomy
Example of a chromosomal mutation in which a zygote ends up with an extra chromosome

12. Chromosomal Mutation

13. Spontaneous Mutations
Occur randomly
Some environmental agents causes
Prolonged exposure to X-rays
Prolonged/excessive exposure to UV radiation
Radiation exposure
Certain chemicals

14. Inheritance of Mutations
Somatic cell mutations are NOT passed on to the next generation
Mutations that occur in sex cells are passed on to the organism’s offspring and will be present in every cell of the offspring.